The control of the synthesis of ribosomes and RNA polymerase will be investigated by measuring the rates of synthesis of ribosomal and RNA polymerase components after infection with lambda rif d 18. In particular, we will try to determine whether the synthesis of any of the ribosomal or RNA polymerase components encoded by lambda rif d 18 stimulates the expression of ribosomal or polymerase genes that are not carried by this phage. Several experiments will also be performed that are directed at an understanding of transposition, which is a novel form of genetic recombination. In particular we will investigate whether ISl codes for any polypeptides or RNAs. We will also investigate whether Tn5 can transpose if there are different sequences at the ends of the inverted repeats, and whether there are hot-spots for the transposition of Tn5 into E. coli chromosome.